The need for the present invention results from expectations within the telecommunications industry that, either voluntarily or by regulatory fiat, a more liberalized interconnection environment for telecommunications signalling will be introduced. Liberalized interconnection can also be characterized as an "open access" environment. In view of this, care must be taken by the operator of a signalling network to protect the vital telecommunications functions dependent upon and enabled by that network, from any impairment resulting from this liberalized interconnection.
The concepts of the present invention may apply to a variety of out-of-band signalling networks. The preferred embodiment however, relates to a Signalling System Number 7 (equivalently known as either "SS7" or "Common Channel Signalling (Number) 7" (CCS7)) compliant signalling system commonly used in a public switched telephone networks.
A signalling network is a critical resource enabling the delivery of telecommunications services to end users by its operator. The operator must protect its own network (equivalently identified within the present invention as the internal (operational) domain) from impairment due directly or indirectly to interconnection with other (external) signalling networks. In particular, all messages received from an external operational domain must be validated to ensure that they conform to any applicable agreements governing the communications to be exchanged between the internal and external domains.
The process of examining and validating the signalling traffic crossing the interface between the internal network and an external network is called "mediation". Mediation is, therefore, a set of procedures and capabilities that act together to maintain both service; network, and physical element integrity, in the face of external influences. In effect, mediation is technological insurance against threats which are perceived to exist from outside the internal signalling network.
Mediation can be carried out in any signalling point (SP) in the internal network either as a part of, or the entire function of, that SP. A Signalling Mediation Point (SMP) is an SS7 Signalling Point deployed within a signalling network whose entire function is "mediation". The mediation function is invoked whenever there is a need for communication between an internal domain's Signalling Point and an external domain's Signalling Point. Thus, Mediated Access provides access to the internal SS7 network domain while preserving its integrity and security, including verification (adherence) to those capabilities defined in either a contractual obligation, mutual business agreement or regulatory directive/tariffed structure.
An attempt to provide mediation of an open AIN interface is offered in U.S. Pat. No. 5,430,719, of Weisser, Jr. In this patent, a table carrying the unique transaction identifiers with service process identifiers generated by various service provider applications is created. Mediation rules include testing the table to determine whether the Directory Number referenced in a message request from a service provider application is a customer of the service provider, whether trunk group routing requests are valid for the service providers and whether any access to, or particular levels of access to, certain network elements are authorized for the service provider requesting the service.
The teachings of Weisser are limited to mediating access to the internal domain via SCPs located within the domain and specifically in an AIN environment and not to the mediation of all signalling traffic entering or leaving the internal domain as a direct result of interconnection.
The problem which has been encountered to date with the development of the Signalling Mediation Point (SMP) is that sufficiently general methods and rules have not been provided so that mediated access can be applicable across a wide range of interconnection complexity ranging from a simple connection to a single external Signalling Point up to interconnections with external networks of arbitrary size and complexity.
Another problem with existing SMP development is that designs are often limited to a specific subset, Application Part or `user part` of the SS7 protocol architecture.
A need therefore exists for providing a method for developing signalling network mediation which overcomes the shortcomings of the prior art.